1. Field of Invention
The present invention relates to projectors capable of displaying images.
2. Description of the Related Art
Currently a projector displays images in such a way that light emitted from an illumination optical system is modulated according to image data (image signals) by liquid crystal light valves, for example, and the modulated light is projected onto a screen. The projector for displaying color images is provided with a colored-light-separating optical system for separating light emitted from the illumination optical system into three colored light and a colored-light-combining optical system for combining three modulated light emitted from respective three liquid crystal light valves. A crossed dichroic prism is used as the colored-light-combining system, the crossed dichroic prism being provided with the two types of selection films formed at a substantially X-shaped interface between four rectangular prisms. The projector can include a plurality of optical parts assembled with each other. The plurality of optical parts are generally mounted onto a common base frame.
With the above described projector, it has been difficult to mount the crossed dichroic prism accurately in a predetermined position of the base frame. Accordingly, the present invention provides a technology for accurately mounting a prism such as a crossed dichroic prism used for a projector to a predetermined position of a base frame, thereby solving the above-described problems found with respect to the conventional technology.
In order to solve at least one part of the above-described problem, a first device according to the present invention, which is a projector for displaying color images, can include an illumination optical system, a colored-light-separating optical system for separating light emitted from the illumination optical system into first, second, and third colored light which are three color components, respectively, first, second, and third electro-optical devices which modulate the first, second, and third colored light, respectively, according to image data, and produce first, second, and third modulated light, respectively, and a colored-light-combining optical system for combining the first, second, and third modulated light. The projector can further include a projection optical system for projecting the combined light emitted from the colored-light-combining optical system, and a base frame for mounting a plurality of optical parts which are disposed in a light path extending from the illumination optical system to the projection optical system. Furthermore, at least one of the colored-light-separating optical system and the colored-light-combining optical system can be provided with a prism that includes a selection film formed therein for selecting light having a predetermined range of wavelengths, and the prism is bonded directly to the base frame.
In the first device, since the prism is directly bonded to the base frame, the prism can be mounted accurately to a predetermined position on the base frame in comparison with a case that the prism is bonded to the base frame with screws. The prism may be a colored-light-combining prism which forms the colored-light-combining optical system. The colored-light-combining prism may comprise, for example, four columnar prisms sectioned by a substantially X-shaped interface and the two types of selection films formed at the substantially X-shaped interface.
In the above device, the colored-light-combining prism is preferably bonded to the base frame with an ultraviolet-curing resin. When an ultraviolet-curing resin is used as described above, the colored-light-combining prism and the base frame can easily be bonded to each other in a relatively short time.
A mark is preferably provided in the vicinity of a substantially square region of the base frame to which the colored-light-combining prism having a substantially cubic shape is bonded, the mark indicating a position of mounting the colored-light-combining prism. The mark may be, for example, a hole or a concavity provided in the center of the substantially square region to which the colored-light-combining prism is bonded. With this arrangement, the colored-light-combining prism can easily be mounted in a predetermined position of the base frame.
In the above device, the base frame preferably comprises a metal material at least in the region to which the colored-light-combining prism is bonded. With this arrangement, temperature rise of the colored-light-combining prism can be suppressed.
In the above device, the first, second, and third electro-optical devices may be three liquid crystal panels, and three liquid crystal light valves which include the three liquid crystal panels, respectively, may be bonded to the colored-light-combining prism. In the above device, the liquid crystal light valves are respectively provided with a polarizing plate disposed at a light-emitting face of the liquid crystal panel and a light transmissive substrate with the polarizing plate bonded thereto and having a heat conductivity of not less than approximately 5 W/mxe2x80xa2K, and each light transmissive substrate is preferably bonded to the colored-light-combining prism. The light transmissive substrate may be made of quartz or sapphire.
When such light transmissive substrates are used, temperature rise due to heat generation in the polarizing plates provided at the light-emitting faces of the liquid crystal panels can be suppressed.
In the above device, the liquid crystal light valves may be respectively provided with a polarizing plate disposed at a light-emitting face of the liquid crystal panel and bonded to the colored-light-combining prism, and the four columnar prisms of the colored-light-combining prism may include a light transmissive material having a heat conductivity of not less than approximately 5 W/mxe2x80xa2K. The light transmissive material may be quartz or sapphire.
When the colored-light-combining prism includes such a light transmissive material, temperature rise due to heat generation in the polarizing plates disposed at the light-emitting faces of the liquid crystal panels can be suppressed. Moreover, there is an advantage that the light transmissive substrates to which the polarizing plates are bonded can be omitted.
The above device may further include three lenses disposed in the vicinities of light-incident faces of the three liquid crystal light valves, respectively. The three lenses may be mounted to a holding frame, which differs from the base frame, and be fixed to the base frame. With this arrangement, the three lenses can easily be mounted to the base frame. For example, when the liquid crystal light valves are bonded to the colored-light-combining prism after the colored-light-combining prism is mounted to the base frame, a workspace for the operation can be ensured.
A second device according to the present invention, which is a projector for displaying color images, can include an illumination optical system, a colored-light-separating optical system for separating light emitted from the illumination optical system into first, second, and third colored light which are three color components, respectively, first, second, and third electro-optical devices which modulate the first, second, and third colored light, respectively, according to image data, and produce first, second, and third modulated light, respectively, and a colored-light-combining optical system for combining the first, second, and third modulated light. The projector that displays color images can further include a projection optical system for projecting the combined light emitted from the colored-light-combining optical system, and a base frame for mounting a plurality of optical parts which are disposed in a light path extending from the illumination optical system to the projection optical system. At least one of the colored-light-separating optical system and the colored-light-combining optical system can be provided with a prism which includes a selection film formed therein for selecting light having a predetermined range of wavelengths. Furthermore, a detachable mounting platform for mounting the prism can be fixed to the base frame, and the prism is bonded to the mounting platform fixed to the base frame.
Since the prism is bonded to the mounting platform fixed to the base frame in the second device, the prism can be mounted accurately in a predetermined position of the base frame in the same manner as in the first device.
In the above device, a mark is preferably provided in the vicinity of a substantially square region of the base frame to which the colored-light-combining prism having a substantially cubic shape is bonded, the mark indicating a position of mounting the colored-light-combining prism. The mounting platform is preferably provided with a hole formed therein through which the mark formed on the base frame can be confirmed from the upper side of the mounting platform. With this arrangement, the prism can easily be disposed in a predetermined position of the base frame when the mounting platform is detachable.
A method for fixing a prism, which includes a selection film formed therein for selecting light having a predetermined range of wavelengths and is included in at least one of a colored-light-separating optical system and a colored-light-combining optical system, to a base frame of a projector for displaying color images. The projector can include an illumination optical system, the colored-light separating-optical system for separating light emitted from the illumination optical system into first, second, and third colored light which are three color components, respectively, first, second, and third electro-optical devices which modulate the first, second, and third colored light, respectively, according to image data, and produce first, second, and third modulated light, respectively, the colored-light-combining optical system for combining the first, second, and third modulated light; a projection optical system for projecting the combined light emitted from the colored-light-combining optical system, and the base frame for mounting a plurality of optical parts which are disposed in a light path extending from the illumination optical system to the projection optical system. The method can include the steps of fixing a detachable mounting platform for mounting the prism to the base frame, and bonding the prism to the mounting platform fixed to the base frame.
When the prism is fixed to the base frame in the above-described steps, the prism can easily be disposed in a predetermined position of the base frame when the mounting platform is detachable.